Cheapest priced copy (Dragons of Tarkir): $0.35 at Card Kingdom, near mint, their price list as of .
Dromoka Monument 
Artifact · Uncommon · Dragons of Tarkir · #238
{T}: Add {G} or {W}.
{4}{G}{W}: This artifact becomes a 4/4 green and white Dragon artifact creature with flying until end of turn.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
1 printing · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Dragons of Tarkir | 238 | Uncommon | $0.35 | $0.49 |
4 rulings from Wizards of the Coast
- 25 February 2015If a Monument has any +1/+1 counters on it, those counters will remain on the permanent after it stops being a creature. Those counters will have no effect as long as the Monument isn't a creature, but they will apply again if the Monument later becomes a creature.
- 25 February 2015A Monument can't attack on the turn it enters the battlefield.
- 25 February 2015Each Monument is colorless, although the last ability will make each of them two colors until end of turn.
- 25 February 2015Activating the last ability of a Monument while it's already a creature will override any effects that set its power or toughness to a specific value. Effects that modify power or toughness without directly setting them to a specific value will continue to apply.